Cyclic ketals of 3-keto-17-hydroxy-17-ethynyl-cyclopentanoperhydrophenanthrenes, andmethod of preparing them



Patented July 7, 1942 CYCLIC KETALS OF 3-KE'I0-17-HYDROXY- lI-ETHYNYL-CYCLOPENTANOPERHYDRO- PHENANTHRENES, AND METHOD OF PRE- PARING THEM Homer E. Stavely, Highland Park, N. 1., alsignor to E. B. Squibb a Sons, New York, N. Y., a corporation of New York No Drawing. Application October 11, 1941, Serial No. 414,647

Claims.

This invention relates to, and has for its obiect the provision of, cyclic ketals of 3-keto-17- hydroxy-17-1ethynyl-cyclqpentanoperhydrophenanthrenes, and methods of preparing them.

For brevity and convenience, the term cyclopentanoperhydrophenanthrene" is hereinafter replaced by the apt, telescopically-formed, term cythrene.

The compounds of this invention, especially the cyclic ketals of 3-keto-17-hydroxy-17- ethynyl compounds of the androstane series, are valuable as biologically-active agents and as precursors or intermediates for the preparation of biologically-active agents. This the ethylene ketal of l7-ethynyl-androstenone-3-ol-17, or l'l-ethynyl-testosterone-(ethylene ketal) is an active oral progestational agent.

The compounds of this invention may be prepared by reacting a 3,17-diketo-cythrene-3- (cyclic ketal)obtainable by reacting a 3,17- diketo-cythrene with an aliphatic polyhydric alcohol, as described in Fernholz application Serial No. 407,498, filed August 19, 194lwith acetylene in the presence of an alkali-metal tertiary alcoholate, as described in my Patent No. 2,239,864, dated April 29, 1941. Alternatively, t e compounds of this invention may be prepared by reacting a 3-keto-17-hydroxy-l7-ethynyl-cythrene obtainable by reacting a 3-hydroxy-17-ketocythrene with acetylene in the presence of an alkali-metal tertiary alcoholate asdescribed in the aforesaid patent and oxidizing the resulting 3,17 dihydroxy-17-ethynyl cythrene-with an aliphatic polyhydric alcohol, as described in the aforesaid application.

The following examples are illustrative of the invention:

Example 1 (a) 1.0 g. 3,1'7-androstenedione (A -androstenedione-ii,l7), 0.23 cc. ethylene glycol, and a crystal of p-toluene-sulfonic acid are dissolved in 50 cc. benzene, and the mixture is slowly distilled for 4 hours. 10 cc. of 2% alcoholic KOH is then added, followed by water, and the re-,

action mixture is extracted with ether. The ether is removed from the extract, and the residue dissolved in a small quantity of methanol; on standing for about 16 hours, 0.5 g. of a crystalline product is obtained, consisting of a mixture of monoand di-(ethylene ketals) of 3,17- androstenedione.

The oily mother liquor from which the mixture of ketals crystallizes is reconverted into 3,17-androstenedione by refluxing for 1 hour in alcohol containing a few cc. of dilute hydrochloric acid, then adding water, extracting with ether, evaporating, and recrystallizing the residue. The unused 3,17-androstenedione is thus recovered almost quantitatively, and can be returned to the ketal-forming treatment.

(b) The mixture of ketals is dissolved in benzene, filtered through a 2 x 21 cm. column of alumina, and the column gradually washed through with benzene. The first cc. of benzene contains 0.2 g. 3,1'l-androstenedione-di- (ethylene-ketal), which, on recrystallization from methanol, is obtained in the form of feathered needles melting at 173 C. The washing is then continued with benzene containing 10% alcohol, and on removal of the solvent from this wash, 0.3 g. of 3,17-androstenedione-3-(ethylene ketal) is obtained. It crystallizes from methanol in the form of thick prisms melting at 194 0.; this, however, is an unstable modification, which, on solidifying from the melted form, is transformed into the more stable modification melting at 202 C. The thus-obtained mono- (cyclic ketal) has the ketal group on Ca, as clearly indicated by the facts that it does not have the characteristic absorption spectrum of an pp-unsaturated ketone and that it is transformed into testosterone-(ethylene ketal) on hydrcgenation.

(c) l g. A -3,l'I-androstenedione-3-(ethylene ketal) is dissolved in 100 cc. dry ether and placed in a round-bottom flask fltted with a stirrer and mercury seal. Purified, dried acetylene is bubbled through the stirred solution for about 30 minutes at room temperature; then, while continuing the acetylene addition and stirring, a solution of potassium tertiary amylate (prepared from 1 g. potassium and 15 cc. dry tertiary-amyl alcohol) is added dmpwise, and thereafter the acetylene addition and stirring are continued for about 5 hours. The reaction mixture is then poured into 200 cc. slightly alkaline water, and thoroughly extracted with ether; and the ether solution is washed with water, dried, and evaporated to dryness in vacuo. The residue, 17- ethynyl-testosterone-(ethylene ketal), is recrystallized from benzene several times, the melting point reaching a constant value of 252-254 C. (uncorrected); [G] -97i3- Example 2 800 mg. 17-ethynyl-androstenediol-Zi,l7 (cf. the aforesaid patent) is oxidized with 1 g. aluminum isopropylate in 25 cc. dry cyclohexanone and 50 cc. dry toluene. The mixture is refluxed for 1 hours, cooled, poured into 300 cc. 2NHC1 and extracted with ether; and on evaporating the ether, steam-distilling the residue to remove cyclohexanone, and filtering of! the resulting precipitate and recrystallizing it from ethyl acetate, 450 mg. of l'l-ethynyl-testosterone (melting at 265 C.) is obtained.

800 mg. 17-ethynyl-testosterone and 3)!) cc. ethylene glycol are dissolved in 50 cc. dry benzene, a few crystals of p-toluenesulfonic acid are added, and the mixture is heated to boiling and the benzene slowly distilled off for 4-5 hours. cc. 2% KOH in alcohol is then added, followed by 100 cc. water, and the mixture is extracted with ether; the ether solution is washed, dried, evaporated to dryness, and the residue crystallized from benzene. On repeated crystallization, the melting point is raised to a constant value of 252-254 C. (uncorrected). The product obtained, 17-ethynyl-testosterone-(ethylene ketal), is identical with that obtained in Example 1.

The ethylene glycol used in the foregoing example may be replaced by 1,2-propylene glycol, trimethylene glycol, glycerol, various carbohydrates, and other aliphatic polyhydric alcohols; and 3,17-androstenedione-3(cyclic ketals) derived from such other aliphatic polyhydric alcohols may be used in place of the 3,17-androstenedione-3 (ethylene ketal) in Example 1.,

The invention is manifestly applicable to the production of cyclic ketals of 3-keto-17-hydroxyl7-ethynyl-cythrenes other than of 3-keto-17- hydroxy-l'l-ethynyl androstene (ethynyl-testosterone). Thus, the procedure of Example 1 is manifestly applicable to the treatment of 3- (cyclic ketals) of other 3,17-diketo-cythrenes, inter alia:

3,17-androstanedione A -androstenetrione-3,11,17 A -androstadienone-3J7 A -androstenedione-3,17 A -androstenedione-3,17 M-androstenetrione-tifi,17 5,6-oxo-androstanedione-3,17

Cyclic ketals of 3-keto-1'I-hydroxy-17-ethynylcythrenes other than of ethynyl-testosterone are manifestly also obtainable by the procedure of Example 2, using other 3-oxy-17-hydroxy-17- ethynyl-cythrenes in place of that used in that example, the ethynyl compounds being obtained (cf. the aforesaid patent), by reacting acetylene with 3-oxy-l7-keto-cythrenes, inter alia:

Androsterone Androstanediol-3,11-one-17 A -androstanediol-3,1l-one-l7 A -androstenediol-3,1l-one-17 When forming cyclic acetals from I'Z-ethynyltestosterone and other A -3-keto-cythrenes, it is believed that there is a shift of the double bond to the 5-6 position on formation of the cyclic ketal; but it is not intended that the invention be limited by any theoretical explanations.

The invention may be variously otherwise embodied, within the scope of the appended claims.

I claim:

1. A cyclic ketal of a 3-keto-1'7-hydroxy-17- ethynyl-cythrene.

2. An ethylene ketal of a 3-keto-l7-hydroxy- 17-ethynyl-cythrene.

3. A cyclic ketal of a 3-keto-17-hydroxy-17- ethynyl compound of the androstane series.

4. A cyclic ketal of 17-ethynyl-testosterone.

5. I'Z-ethynyl-testosterone-(ethylene ketal).

6. The method of preparing a cyclic ketal of a 3-keto-17-hydroxy-l7-ethynyl-cythrene, which comprises reacting a 3,17-diketo-cythrene-3-- (cyclic ketal) with acetylene in the presence of an alkali-metal tertiary alcoholate.

7. The method of preparing a cyclic ketal of a 3-keto-17-hydroxy-17-ethynyl-cythrene, which comprises reacting a 3-keto-l'l-hydroxy-l7 ethynyl-cythrene with an aliphatic polyhydric alcohol.

8. The method of preparing a cyclic ketal of 'l'Z-ethynyl testosterone, which comprises reacting a 3,17-androstenedione-3-(cyclic ketal) with acetylene in the presence of an alkali-metal tertiary butylate. I

9. The method of preparing a cyclic ketal of 17-ethynyl testosterone, which comprises reacting l'l-ethynyl-testosterone with an aliphatic polyhydric alcohol. 1

10. The method of preparing a cyclic ketal of a 3-keto-l7-hydroxy-17-ethynyl-cythrene, which comprises reacting a 3-keto-17-hydroxy-17- ethynyl-cythrene with an aliphatic polyhydric alcohol in the presence of p-toluenesulfonic acid.

HOMER E. STAVELY. 

